Microwave-induced spontaneous deformation of purple potato puree and oleogel in 4D printing

Abstract With the extensive use of 3D printing technology in food, 4D printing technology arises at the historic moment. The purpose of this study is to utilized microwave heat as an external thermal stimulus, fabricate automatic change shape features of food 4D printing products. Oleogel and purple potato puree with different ratio of solid to liquid were used for dual nozzle printing. The differences of rheological properties, dielectric properties, water distribution and Young's modulus between oleogel and different formulations of purple potato puree were analyzed as well as the printability of the slurry and the caused of shape-changing by microwave treatment were characterized. Due to the great difference in microwave absorption capacity and rheological properties between purple potato puree and oleogel, the shape of purple potato puree can change spontaneously during microwave treatment. The bending angle and model height were taken as the main parameters of deformation, and the influence of time and power of microwave on the shape-changing was analyzed. The results show that there is a linear relationship between the microwave power and time and the bending angle of the model in a certain range, which provides a new idea for the spontaneous deformation of food 4D printing.